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gushing air vent in return

joeyB Member Posts: 3
Bare with me fairly new to working on steam boiler systems. Have a boiler in an apartment building that has an air vent on a return up above boiler. Have a two pipe system. Boiler has not been taken care of. have cleaned FandT traps reworked return that runs along floor to get some grade to boiler. Lowered pressure setting to below 1 psi to get water from gushing out air vent is new. with lower psi it now just spits. have numerous return lives the tie into the return riser. seems to me it is filling up and pushing water out the vent. vent is seven inches of the pipe it is mounted on. any and all suggestion are appreciated.


  • gerry gill
    gerry gill Member Posts: 3,078
    one suggestion,

    measure the distance from the lowest horizontal return pipe, (probably the one with the air vent) to the boilers normal water line..divide that by 1.75 and that is the maximum number of ounces the boiler pressure can be allowed to go without water flooding the return..and that also doesn't allow any loss from friction..so in reality the boiler pressure would have to be a bit less even..i use a clear plastic tube temporarily attached to a boilers drain valve and trown up an over a ceiling pipe to 'see' how high the water is being pushed up the 'B' dimension pipes.
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • joeyB
    joeyB Member Posts: 3
    gushing return air vent

    then vent is actually up high in between the floor joist. when i go back im gonna take a pic of the retun layout and attach it on here. the vent is prob a good three to four feet above boiler water level. thanks for the suggestion will def try that out. thanks
  • Return pipes pitch

    The wet return should be well below the boiler's waterline, but needs no pitch to get the water back to the boiler, as the condensate coming down from the dry return will keep the flow going. Think of a hose, with very slight pressure which has no problems with slope.

    Give us some pictures of the boiler piping, as that may be shooting more water than steam up into the system, if mis-installed.--nbc
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